1. Field of the Invention
The present invention relates in general to a grinding machine of the type wherein a workpiece rotatable about an axis is ground by effecting relative infeed movement between the workpiece and a rotating grinding wheel. More particularly, it relates to a control apparatus for such a grinding machine capable of modifying a grinding condition such as infeed rate of a grinding wheel based upon the rigidity of a workpiece to be ground.
2. Description of the Prior Art
A grinding machine has been known in which the infeed rate of a wheel head rotatably carrying a grinding wheel is controlled to maintain the flexing amount of a workpiece constant. The flexing amount is calculated from the difference between a transient size of the workpiece measured by a sizing device and a transient position of the wheel head. In the grinding machine, the lower the workpiece rigidity is and the more flexible the workpiece is, the slower the infeed rate of the grinding wheel becomes. Thus, it is possible for the grinding machine to precisely machine workpieces without creating any chatter mark, heat-affected layer and the like. However, in order to measure the transient size of a workpiece during a grinding operation, the grinding machine requires the use of a signal output from a measuring head of the sizing device. Therefore, in a dead-stop grinding mode employing no sizing device, such a control method cannot be practiced, and any grinding operation cannot be performed in a condition suitable for the rigidity of any workpiece.